Field of the Invention
The present invention relates to a substrate processing apparatus including a plurality of adjacent chambers, which performs various kinds of processings on a liquid crystal glass square substrate, a semiconductor wafer or the like (hereinafter referred to simply as xe2x80x9csubstratexe2x80x9d) while transferring the substrate between the chambers.
Description of the Background Art
Among conventional apparatus for performing a substrate processing such as film formation and cleaning in processing chambers while transferring a substrate between the chambers are those disclosed in Japanese Patent Application Laid Open Gazettes 5-217918 and 5-217919. In these substrate processing apparatus, since the substrate processing is apt to be easily affected by contamination due to unnecessary natural oxide films formed by oxygen and deposit of particles, the chambers are supplied with N2 (nitrogen) gas as an inert gas to increase pressures of their inner atmosphere, thereby discharging oxygen in the chambers and suppressing inflow of oxygen and particles from the outside, to prevent contamination of substrate.
Further, opening a gate valve of a chamber during loading of the substrate into the chamber and closing it after processing and unloading of the substrate, the above apparatus performs the various kinds of processings of the substrate in the chambers while sequentially transferring the substrate.
Anyway, in the above apparatus, all the chambers are supplied with the same amount of N2 gas in a unit of time. Further, from the nature of the substrate processing, it is required that a concentration of oxygen should become lower from the upstream of a substrate processing process to the downstream. Therefore, in order to set low oxygen concentration in the chambers on the downstream, it is necessary to set the same oxygen concentration in all the chambers as the chambers on the downstream which need the lowest concentration, and that needs supply of a large amount of N2 gas.
Moreover, the above apparatus requires longer time to supply a large amount of N2 gas so as to fill the chambers with N2 gas, which include air flowing therein from the outside in loading a substrate from the outside and unloading a processed substrate to the outside (hereinafter, the required time is referred to as xe2x80x9cpurge timexe2x80x9d).
The present invention is directed to an apparatus for processing a substrate. According to the present invention, the apparatus comprises: (a) a transfer chamber having transfer means for transferring the substrate; (b) a group of chambers arranged around the transfer chamber, the group of chambers comprising (b-1) a loading chamber for loading the substrate into the transfer chamber; (b-2) an unloading chamber for unloading the substrate from the transfer chamber; and (b-3) a plurality of processing chambers for processing the substrate; (c) inert-gas supply means for supplying at least the transfer chamber, the unloading chamber and the plurality of processing chambers with an inert gas; and (d) control means for controlling inner pressures of the unloading chamber, the transfer chamber and each of the plurality of processing chambers so that the following first inequality is satisfied at least during an inter-chamber transfer of the substrate, the first inequality being expressed as pU greater than pT greater than pS where pU represents an inner pressure of the unloading chamber, pT represents an inner pressure of the transfer chamber, and pS represents an inner pressure of each of the plurality of processing chambers.
Preferably, the control means controls the inner pressures of the unloading chamber and the transfer chamber so that the following second inequality is satisfied at least immediately before the inter-chamber transfer of the substrate, the second inequality being expressed as pL greater than pT where pL represents an inner pressure of the loading chamber.
The apparatus of the present invention eliminates the necessity for keeping the whole apparatus at high pressure by supplying the inert gas since it is not necessary to set the same oxygen concentration in the whole apparatus as that in a chamber where the lowest oxygen concentration is required. Without the need for a large amount of inert gas, the processings of substrate can be performed by supplying small amount of inert gas, with less contamination of the substrate at lower cost.
Further, even when the supply of inert gas is performed in a state where a large amount of air flows in from the outside during transfer of the substrates, it is not necessary to supply a large amount of inert gas to the whole apparatus and therefore the purge time for the inert gas becomes shorter.
Preferably, the apparatus further comprises (e) inner-atmosphere outlet means connected to the loading chamber.
When the loading chamber is supplied with the inert gas to lower the inner oxygen concentration, the supply of the inert gas can be performed after discharging inner air of the loading chamber, requiring a smaller amount of inert gas. Therefore, the processings of substrate can be achieved at much lower cost with shorter purge time.
Preferably, each or any of the plurality of processing chambers comprises a processing body for performing a processing on the substrate; and a sub-transfer unit for transferring the substrate between the processing body and the transfer chamber.
Since the atmosphere containing a large amount of oxygen and particles in the processing body is not sucked directly into the transfer chamber also when the substrate is transferred between the processing body and the transfer chamber, unnecessary supply of inert gas is avoided and the processing of substrate can be achieved at much lower cost.
An object of the present invention is to provide a substrate processing apparatus capable of performing a processing of substrate with less contamination, with a shorter purge time, at lower cost.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.